Happened to me too. The left hinge is held into place by four screws, you can see that in step 7 of the repair guide (in the upper-left corner of the pc). Unfortunately the screw nuts (I think that's the term) tend to pop out of their plastic socket, causing the hinge to push on the upper case and break it apart. I just stuck the screw nuts back into place with some super glue, and loosened the hinge bolt a bit to prevent future damage. Now the hinge requires less strength to open and works just fine. You should also check the little screw holding the power button into place, that might have popped out too. Hope it helps, and sorry if I made mistakes (english is not my motherlanguage).